1. Field of Invention
The invention concerns a process for laser beam welding with reduced formation of end craters.
During laser beam welding a so-called end crater forms at the end of the weld seam. The end crater is formed by the volume shrinkage of the solidifying melt after the laser beam reaches the seam end and is switched off or repositioned. The end crater acts as a geometric notch or groove and degrades the mechanical properties, and in particular the operational stability, of the weld seam, so that holes or tears in the area of the end crater can occur.
2. Related Art of the Invention
For reducing the formation of end craters, it is taught in DE 196 30 521 A1 to reduce the laser output at the seam end (so-called “power ramp”) or to increase the weld speed (so-called “speed ramp”).
Similar methods involving reducing the laser power or defocusing the laser beam are disclosed in DE 102 29 744 A1, JP 551 14 490 A and JP 602 16 987 A.
These procedures reduce the problem slightly, but generally not adequately.
The task the present invention is thus comprised therein, of providing a laser weld seam with reduced end craters and a process for production thereof.